Dental mill blanks are blocks of material from which dental restorations are formed. Dental mill blanks come in a variety of shades and translucencies. The dental professional selects the shade and translucency of the dental mill blank for the dental restoration in an effort to best match the natural shade and translucency of the patient's natural dental anatomy. These natural dental anatomies, however, have a variety of shades and translucencies that are very difficult to capture.
This difficulty arises because natural dental anatomies (e.g., natural teeth) have a gradient of shades and translucencies extending from the gingival region to the incisal edge/occlusal surface due to the internal structure of the teeth. In an attempt to mimic this gradient, dental mill blanks have been formed with multiple flat planar layers, where each layer has at least one different shade and/or translucency. Unfortunately, dental restorations formed from these dental mill blanks have transitions between the flat planar layers that are perceived to be unnatural. Other attempts to mimic the gradient include dental mill blanks that have a discrete shape of material with one shade and/or translucency and a surrounding layer with another shade and/or translucency. Examples of such dental mill blanks include VITABLOCS® RealLife® (Vita Zahnfabrik H. Rauter GmbH & Co., Bad Säckingen, Germany; or CEREC® Blocks C In (Sirona Dental Technologies, Bensheim, Germany)). Forming dental restorations from these dental mill blanks is, however, difficult because they require precise positioning of the restoration design within the dental mill blanks during milling in order to achieve a desired aesthetic result.
As such, there is a need in the art for dental mill blanks that allow for both simple positioning of the restoration design for milling and that will produce a dental restoration with a gradient of shades and translucencies having a natural appearance.